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Own opclass and LIKE problem again! 2+ messages / 2 participants [nested] [flat]
* Own opclass and LIKE problem again! @ 2004-04-26 10:07 Antal Attila <antal.attila@ritek.hu> 0 siblings, 0 replies; 2+ messages in thread From: Antal Attila @ 2004-04-26 10:07 UTC (permalink / raw) To: pgsql-sql Hi! Thank you very much the answers for my previous 'Multi ordered select and indexing' question! I tried your suggestions, and those are working well. We found a problem when used '(-col2)' instead of 'col2 DESC'. This solution working as a functional index and in our experience when the planner evaluates the cost of using this functional index, it uses 0.5% of the table's size. Usually this estimate is bad, and the query is slow. Why is it working such? Preferably should I ask this on the HACKERS or PERFORMANCE list? But my main question how can I force the LIKE operator for using my own operator class. I can create own LIKE operator, but it won't use my reverse order operator class (and its indexes). How can I exchange the standard LIKE operator with my own, which use my special reverse order indexes? For examle: (~~ means LIKE) col ~~ 'asd%' working as ((col >= 'asd'::text) AND (col < 'ase'::text)) I'd like to see the next: col /~~ 'asd%' working as ((col />= 'asd'::text) AND (col /< 'ase'::text)) Can somebody help us? Thanks in advance. Antal Attila ^ permalink raw reply [nested|flat] 2+ messages in thread
* Own opclass and LIKE problem again! @ 2004-04-26 10:11 Atesz <atesz@ritek.hu> 0 siblings, 0 replies; 2+ messages in thread From: Atesz @ 2004-04-26 10:11 UTC (permalink / raw) To: pgsql-sql Hi! Thank you very much the answers for my previous 'Multi ordered select and indexing' question! I tried your suggestions, and those are working well. We found a problem when used '(-col2)' instead of 'col2 DESC'. This solution working as a functional index and in our experience when the planner evaluates the cost of using this functional index, it uses 0.5% of the table's size. Usually this estimate is bad, and the query is slow. Why is it working such? Preferably should I ask this on the HACKERS or PERFORMANCE list? But my main question how can I force the LIKE operator for using my own operator class. I can create own LIKE operator, but it won't use my reverse order operator class (and its indexes). How can I exchange the standard LIKE operator with my own, which use my special reverse order indexes? For examle: (~~ means LIKE) col ~~ 'asd%' working as ((col >= 'asd'::text) AND (col < 'ase'::text)) I'd like to see the next: col /~~ 'asd%' working as ((col />= 'asd'::text) AND (col /< 'ase'::text)) Can somebody help us? Thanks in advance. Antal Attila ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2004-04-26 10:11 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2004-04-26 10:07 Own opclass and LIKE problem again! Antal Attila <antal.attila@ritek.hu> 2004-04-26 10:11 Own opclass and LIKE problem again! Atesz <atesz@ritek.hu>
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